Electric discharge tube for use at very high-frequencies and ultrahigh frequencies



Nov. 30, 1954 G. H. P. ALMA ETAL 2,695,972

FREQUENCIES ELECTRIC DISCHARGE TUBE FOR USE AT VERY HIGH AND ULTRAHIGH FREQUENCIES Filed March 27, 1953 v, E Q Q. 001/, 9M 77 W b A k J! v l H m a 4, q i 5 k g v m 5 7 2 & f

INVENTQRS QEERWT H ENDRIK AGENT United States Patent ELECTRIC DISCHARGE TUBE FOR USE AT VERY HIGH-FREQUENCIES AND ULTRAI-IIGH FRE- QUENCIES Gerrit Hendrik Petrus Alma and Klaas Rodenhuis, Eindhoven, Netherlands, assignors to Hartford National Bank and Trust Company, Hartford, Conn., as trustee Application March 27, 1953, Serial No. 345,056

Claims priority, application Netherlands April 24, 1952 2 Claims. (Cl. 313-263) This invention relates to an electric discharge tube for use at very high frequency and ultra-high frequency (higher than 30 mc./s.) and more particularly to the high-frequency conduction from cathode to lead-through conductor of such a tube.

In tubes for use at such high frequencies the cathode is, as a rule, secured in a carrier body which is fixed in position in the tube after the correct spacing between the cathode and a subsequent electrode has been adjusted. The high-frequency currents from the cathode are in this case carried off through a disc-shaped lead-through member sealed into the wall of the tube, for example, in that the space between carrier body and lead-through member is filled up at least in part with solder. In order to permit exhaustion of the space above and under the cathode, the carrier body is provided with some apertures which are closed by fine metal gauze, in order to avoid penetration of metal particles and dust from the space under the cathode into the electrode space.

Since such high-frequency currents in practice flow only superficially, it is important that the soldered 1omt between the carrier body for the cathode and the leadthrough member should be reliable. However, it has been found that such is not always the case in practice, so that dilferent tubes of the same type relatively exhibit great differences in high-frequency resistance, since the soldering process cannot take place until the electrodes have been mounted and the tube has substantially been closed, the solder fusing during the process of degassing the tube.

According to the invention, the said difficulty is avoided in that in an electric discharge tube for use at very high frequency and ultra-high frequency, in which the cathode is secured on a perforated carrier body, fixed in the tube and connected in an electrically conductive manner to an annular disc-shaped lead-through member sealed into the wall of the tube, the high-frequency conduction from the cathode to the lead-through member is effected through a thin annular disc of fine metal gauze which, on the one hand, is soldered to the carrier body and, on the other, urged through part of its surface, by means of a spring, against the surface of the lead-through member. The annular disc of gauze preferably consists, at least superficially, of conductive metal such as copper or silver. As a rule, the lead-through member is likewise silvered superficially. Since a large portion of the annular disc engages the lead-through member, a highly reliable contact is ensured. Due to the use of gauze for the annular disc, resilient deformation is possible, so

Patented Nov. 30, 1954 that the cathode may be given the right position without causing the contact surfaces of annular disc and leadthrough conductor, which engage one another under the action of the spring, being spaced apart.

In order that the invention may be readily carried into effect, it will now be described with reference to the accompanying drawing showing, by way of example, one embodiment of a tube according thereto.

In the figure, reference numeral 1 indicates the cathode which is secured in a carrier body 2, the edge 3 of which is turned off and has soldered on it an annular disc 4 of metal gauze according to the invention. After the cathode has been given the right position, a flange 5 of the carrier body is fixed in a cup-shaped lead-through conductor 6 with the use of cement or solder 7. The flange 5 exhibits apertures 8, in order to permit exhaustion of the electrode space. The annular disc 4 of gauze, the apertures of which are smaller than 50 microns, prevents penetration of dust and metal particles from the space of sealed-in contact pins 9 into the electrode space. The extremities 10 of the heating body for the cathode are secured to conductors 11, which are supported by a mica disc 12 and connected to the pins 9 by way of connecting wires 13. Two pins 9 are connected to a filamentary getter holder 14. The electrode space contains a grid 15 and an anode 16, which are led to the exterior by way of disc-shaped lead-through conductors. According to the invention, the annular disc 4 of metal gauze is, on the one hand, soldered to the carrier body 2 at 3 and, on the other, urged by means of a spring 1'7 against the bottom of lead-through conductor 6. The contact surface is very large, so that a reliable conduction of the high-frequency currents from the outer surface of cathode 1 via body 2 and annular disc 4 to the outer surface of lead-through conductor 6 is ensured. This is necessary, since the high-frequency currents cannot flow from the inner surface of the leadthrough conductor, which in this case is cup-shaped, through the material to its outer surface.

Although one determined embodiment has been described, the invention is also applicable to tubes of different type. Thus, it is possible to use a cylindrical arrangement of the electrodes, whilst the lead-through conductor 6 may likewise be disc-shaped.

What we claim is:

1. An electric discharge tube for use at frequencies higher than 30 mc./s. comprising a cathode, a perforated carrier body fixed in the tube and supporting the cathode, an annular disc-shaped lead-through member sealed into a wall of the tube and electrically connected to the carrier body, a high-frequency conductive member comprising a thin annular disc of fine metal gauze secured to the carrier body, and resilient means urging a portion of said gauze against the surface of the lead-through member.

2. An electric discharge tube as claimed in claim 1, wherein the metal gauze consists, at least superficially, of material of high conductivity.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,164,477 Smith July 4, 1939 2,367,332 Bondley Jan. 16, 1945 

